Bistable multivibrator for operating a pair of control coils



Aug. 8, 1967 T. E, MYERS BISTABLE MULTIVIBRATOR FOR OPERATING A PAIR OF CONTROL COILS I Filed Nev. 12, 1964 ZZ id 34 arr INVENTOR. 774M; [fix/q;

United States Patent 3,335,333 BISTABLE MULTIVIBRATOR FOR OPERATING A PAR OF CONTROL COILS Thomas E. Myers, St. Charles, 111., assignor to Ideal Industries, Inc, Sycamore, 111., a corporation of Dela- Ware Filed Nov. 12, 1964, Ser. No. 410,596 7 Claims. '(Cl. 317149) ABSTRACT OF THE DISCLOSURE This invention relates to a bistable multivibrator, with each side of the multivibrator including an operating coil of a control element.

A primary purpose of the invention is a circuit of the type described which, upon switching from one stable condition to the other, provides an initial surge of current through an operating coil, with the current through the conducting side of the circuit thereafter decreasing to a lower value.

Another purpose is a bistable multivibrator which may be switched from one stable condition to the other, by means of human contact with a touch control surface or antenna.

Another purpose is a control circuit of the type described utilizing a pair of relay coils, with each coil being arranged to hold the relay in a given position.

Other purposes will appear in the ensuing specification, drawings and claims.

The invention is illustrated diagrammatically in the attached circuit diagram illustrating one form of a control circuit of the type described.

The invention may be described in general as a control circiut suitable for actuating a pair of relay coils whose contacts perform a control function. The signal for actuating the circuit may come from one or more antennas. Each antenna may have a surface positioned for and adapted for human contact so that the potential of the body applied to the antenna is sufiicient to operate the circuit. In the alternative, a single antenna may be replaced by two adjacent antennas positioned such that human contact bridges or shorts the two antennas together to thereby connect a previously established voltage, for example from one side of the source, to operate the circuit.

In still another form of operation, human contact at the touch surface may be effective through a momentary contact shorting arrangement to apply a predetermined voltage to an antenna to operate the circuit. Such a circuit would be particularly useful when a person contacting the touch surface is wearing gloves. In another form of operation, each antenna may be replaced by a number of separate antennas positioned at different points, with the application of a potential to any one of these antennas being suflicient to operate the circuit. For example, it may be desirable to turn on an electric light from any one of a number of different locations. Each location will have an antenna and the antennas will all connect at a common point, so that the application of a potential to any one of the antennas would be effective to turn on an electric light or to perform some other type of control function.

In the circuit shown, there are a pair of relay coils. Each coil may be part of a latching relay or any other type of holding relay. Latching relays are desirable in some situations, but the circuit has broader application. In any event, current passing through either one of the coils is effective to switch the relay from one operative position to another. The relay may be a mechanical latching relay, a magnetically latching relay, or any other type of holding relay which will remain in a certain position once the contacts have been moved into that position.

In the drawing, a typical 117-volt AC source may connect to lines 10 and 12. The control circuit may include a resistance 14, which is a timing resistance, and is connected to line 10 and to the cathode 16 of a diode indicated generally at 18. The anode 20 of the diode 18 may be connected to elements 22 and 24 of tubes 26 and 28 respectively. The tubes 26 and 28 may be gas tubes, for example glow discharge tubes, or any other satisfactory type of tube which will ionize when a certain potential is placed on its gate. An NE77 is a satisfactory type of tube. Tubes 26 and 28 each have gates 30 and 32 respectively which are connected to antennas or touch contact surfaces 34 and 36. In some applications it may be desirable to place a high resistance between the antenna or contact surface and the gate of the tube. Elements 38 and 40 of tubes 26 and 28 are each connected to coils 42 and 44, which coils may be a part of a latching or holding relay. The lower half of coil 42 is connected directly to line 12. The lower half of coil 44 is connected through a resistance 46 to line 12. The circuit is completed by a capacitor 48 which is connected to the anode 20 of diode 18 and to the variable intermediate tap 50 of resistor 46.

When a voltage is initially applied to the circuit, the left-hand side of the bistable circuit will conduct as tube 26 will ionize. The current path from one side of the source to the other, through the left-hand side of the circuit includes only resistance 14, diode 18, tube 26 and coil 42. Whereas, the path through the opposite side of the circuit includes resistance 46. Because the paths through opposite sides of the bistable circuit are unequal in their total impedance, the left-hand side of the circuit will always conduct when a voltage is initially applied to the circuit. Tube 26 will be ionized and any residual charge on capacitor 48 will discharge through this tube. Thereafter, tube 26 will conduct and a rather low level of current will flow through coil 42. This low level of current is not of sutficient magnitude to cause the coil to perform any control function. The amount of current necessary for coil operation is more than that supplied from the source. During the period that tube 26 is con ducting, capacitor 48 will charge up to a value determined by the combined resistance of tube 26, the resistance in coil 42 and that portion of resistance 46 in the charging circuit. Even though AC voltage is applied to the circuit, diode 18 will permit tube 26 to remain ionized and capacitor 48 to charge.

After the capacitor has charged up to a predetermined value, which in this case may be on the order of volts considering that the RMS value of the applied voltage is about 117 volts, if contact 36 receives an operating potential, tube 28 will ionize and capacitor 48 will discharge through tube 28 and coil 44. The initial surge of the capacitor as it discharges will provide sufficient current to actuate coil 44 and to cause it to perform a control function. After the capacitor has discharged, tube 28 will remain ionized, but the current flowing through the coil will now be at a substantially lower level, this current only being caused by line voltage. While tube 28 is still ionized and conducting, capacitor 48 will again charge, with the value being determined by the resistance of tube 28, the resistance of coil 44 and that portion of resistance 46 in the charging circuit. Thereafter, if an operating potential is applied to contact 34 tube 26 will ionize and the capacitor will discharge through coil 42 to provide operating current. Subsequent operation of the circuit will be in the same manner in that the circuit will be switched to either the on or off condition as one tube or the other is ionized. The ionization of a partic ular tube is accompanied by capacitor discharge through the coil associated with that tube and the discharging capacitor provides the necessary current for operating the coil.

The intermediate tap 50 of resistor 46 places a certain amount of resistance in each side of the circuit. The voltage on this resistance is effective to maintain the non conducting tube in a cut-off condition. Resistance 46 is variable to compensate for variation in the characteristics of either tube.

The invention should not be limited to gas tubes of the type described as many other types of gated diodes may also be satisfactory. For example, gated semiconductor diodes such as silicon controlled rectifiers may be satisfactory. In like manner, the invention should not be limited to a single relay having two operating coils, as each of the coils shown herein may be used to perform completely separate control functions. 7

Whereas the preferred form of the invention has been shown and described herein, it should be understood that there are inany modifications, substitutions and alterations thereto within the scope of the following claims.

What is claimed is:

1. In a bistable control circuit for connection across a source of power, a pair of coils, each of which performs a control function, a pair of gas tubes each having an anode, cathode and gate, each of said tubes being series connected with one of said coils, means for applying an operating potential to each of said gates, a capacitor, each series combination of a coil and tube being connected across said capacitor, a diode connected between one side of said capacitor and one side of the source, and a resistance connected between the other side of said capacitor and the other side of the source, the application of a potential to one gate causing its associated tube to conduct with said capacitor then discharging through said conducting tube and its associated coil to provide operating current for the coil, said conducting tube remaining in an ionized state, but with insuflicient operating current for the coils until a potential is applied to the gate of the other tube, with the capacitor then discharging through the other tube and its associated coil to provide operating current for said coil.

2. The circuit of claim 1 further characterized in that each of said coils forms a part of a holding relay.

3. The circuit of claim 1 further characterized in that the means for applying an operating potential to each of said gates includes a surface arranged for contact by the human body.

4. The circuit of claim 1 further characterized in that the means for applying an operating potential to each of said gates includes a pair of antennas, with each an-,

tenna being connected to one of said gates.

5. The circuit of claim 1 further characterized in that one of said coils is connected directly to the other side of the source, with the other of said coils being connected through said resistance to the other side of the source.

'6. The circuit of claim 5 further characterized in that said resistance has a variable intermediate connection, with the other side of said capacitor being connected to said variable intermediate connection.

7. In a bistable control circuit for connecting across a source of power, a pair of coils, each of which performs a control function, a pair of gated diodes, each having an anode, cathode and gate, each of said gated diodes being series connected with one of said coils, means for applying an operating potential to each of said gates, a capacitor, each series combination of a coil and gated diode being connected across said capacitor, a diode connected between one side of said capacitor and one side of the source, and a resistance connected between the other side of said capacitor and the other side of the source, the application of a potential to either gate causing its associated gated diode to conduct with said capacitor then discharging through said conducting diode and its associated coil to provide operating current for the coil.

References Cited UNITED STATES PATENTS 2,524,134 10/1950 Palmer 328l06 2,778,978 1/1957 Drew 317l37 3,113,240 12/1963 Perkins et al. 31584.5

MILTON O. HIRSHFI ELD, Primary Examiner. j. A. SILVERMAN, Assistant Examiner. 

1. IN A BISTABLE CONTROL CIRCUIT FOR CONNECTION ACROSS A SOURCE OF POWER, A PAIR OF COILS, EACH OF WHICH PERFORMS A CONTROL FUNCTION, A PAIR OF GAS TUBES EACH HAVING AN ANODE, CATHODE AND GATE, EACH OF SAID TUBES BEING SERIES CONNECTED WITH ONE OF SAID COILS, MEANS FOR APPLYING AN OPERATING POTENTIAL TO EACH OF SAID GATES, A CAPACITOR, EACH SERIES COMBINATION OF A COIL AND TUBE BEING CONNECTED ACROSS SAID CAPACITOR, A DIODE CONNECTED BETWEEN ONE SIDE OF SAID CAPACITOR AND ONE SIDE OF THE SOURCE, AND A RESISTANCE CONNECTED BETWEEN THE OTHER SIDE OF SAID CAPACITOR AND THE OTHER SIDE OF THE SOURCE, THE APPLICATION OF A POTENTIAL TO ONE GATE CAUSING ITS ASSOCIATED TUBE TO CONDUCT WITH SAID CAPACITOR THEN DISCHARGING THROUGH SAID CONDUCTING TUBE AND ITS ASSOCIATED COIL TO PROVIDE OPERATING CURRENT FOR THE COIL, SAID CONDUCTING TUBE REMAINING IN AN IONIZED STATE, BUT WITH INSUFFICIENT OPERATING CURRENT FOR THE COILS UNTIL A POTENTIAL IS APPLIED TO THE GATE OF THE OTHER TUBE, WITH THE CAPACITOR THEN DISCHARGING THROUGH THE OTHER TUBE AND ITS ASSOCIATED COIL TO PROVIDE OPERATING CURRENT FOR SAID COIL. 